There's more to wireless than 802.11 stuff. Alvarion claims 40k pps with their VL and Breezenet-B gear. I haven't tested their claims, but they definitely do a lot better than normal 802.11b gear.
On Sat, May 26, 2007 at 04:46:44PM -0500, Dan wrote: > Well I really have no choice but to use the wireless system that we > have. We don't have any fiber systems out here that we can use. You > say after about the 7th conversation is added, but about how many pps do > you think is the limit? I don't have a lot of experience with this, but > knowing the limit might be helpful for the future. > > Thanks, > Dan. > > John Osmon wrote: > > It's certainly not as rigorous as one might hope, but it does explain > > why common VOIP applications running over 802.11b start to fail when > > around the time the 7th conversation is added to the mix. Which is > > quite consistant with empirical evidence I've collected, and anecdotal I've > > had from others. > > > > My main point is that if the transport is prone to congestion with a > > (relatively) small number of pps, it isn't good candidate for VOIP > > communications. The commonly found wireless schemes in use today fall > > into this category of transport. We'll see things get better as time > > goes on, but the current crop of wi-fi gear simply isn't suited for VOIP > > except in very spcific situations. > > > > I almost feel sorry for the WISPs that have built out neworks with > > 802.11b backahul links. I've *seen* some of them staring at MRTG > > graphs saying "but there's less than 1 Mbps on that link! We can't > > be the cause of your VOIP problems..." As we all know -- the pps > > numbers are more imporportant than the bandwidth nubmers in most > > situations. > > > > This has drifted too far from the 'c' in 'cnsp' -- I'm going to go back > > to lurking... > > > > > > > > On Sat, May 26, 2007 at 11:51:42AM -0500, Frank Bulk wrote: > > > >> In the paper: "To generate a 64 Kbps flow, 64 bytes packets were sent every > >> 8 milliseconds." > >> > >> This is not how the G.711 codec works...it's normally a 20 msec > >> packetization rate resulting in ~220 byte frames (sans 802.11 headers, I > >> believe). I've seen too much undergraduate start with faulty assumptions > >> such that the results are bogus. The only thing these guys have proven is > >> that lots of small packets cause latency and jitter when the link becomes > >> saturated. No surprise there. > >> > >> Regards, > >> > >> Frank > >> > >> -----Original Message----- > >> From: [EMAIL PROTECTED] > >> [mailto:[EMAIL PROTECTED] On Behalf Of John Osmon > >> Sent: Tuesday, May 22, 2007 11:21 PM > >> To: [email protected] > >> Subject: Re: [c-nsp] VoIP without QoS > >> > >> On Tue, May 22, 2007 at 01:47:15PM -0500, Dan wrote: > >> > >>> We have a voip system we have been running in our department now for > >>> about a year. Only 12 phones, connected through various wireless links > >>> with throughput of up to 40mbit. Speed is definitely not an issue for > >>> us, but we notice glitches with the quality on an ongoing basis. We are > >>> currently implementing qos and are wondering what is the best way? > >>> > >> Most common wireless solutions don't really like a lot of small packets. > >> They tend to have too much overhead in the protocols, and you if you're > >> pushing small packets, you hit a pps limit long before anything comes > >> close to using up the bandwidth you think is available. > >> > >> While trying to research why VOIP over wireless networks, I ran into > >> this paper: > >> http://www.it.uc3m.es/~acuevasr/publicaciones/LCS06.pdf > >> > >> _______________________________________________ > >> cisco-nsp mailing list [email protected] > >> https://puck.nether.net/mailman/listinfo/cisco-nsp > >> archive at http://puck.nether.net/pipermail/cisco-nsp/ > >> > >> > > _______________________________________________ > > cisco-nsp mailing list [email protected] > > https://puck.nether.net/mailman/listinfo/cisco-nsp > > archive at http://puck.nether.net/pipermail/cisco-nsp/ > > > > > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ -- /* Jason Philbrook | Midcoast Internet Solutions - Wireless and DSL KB1IOJ | Broadband Internet Access, Dialup, and Hosting http://f64.nu/ | for Midcoast Maine http://www.midcoast.com/ */ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
